Yes that is quite a differance. The only way you can tell if it is jumping around is to monitor it several times. That was Pretty much a full milli volt drop and that is signifigant. You just have to monitor it against what is thought a stable cylinder like #4 if it is hard to catch it. Rather than across the board every time.


You want to catch it if possible when the engine is rough. That is the only time it can reappear. I know from your descriptions that is hard to do in your case. Try to jot down the values every time you read them.


I believe you well understand now when the engine is ideling smooth there is nothing unusual going on. That last reading is the type of thing you might see for example if you had a delivery valve issue. The only problem is I doubt they can be intermittent. It is also the first time we can hopefully narrow it down to a single cylinder. You have an opportunity to watch as it recovers as well. This is something new as we never had an intermittent condition arrise before using milli volts to locate. If you develop a way to catch it reliably . Change the injector with the number one cylinder but still monitor that cylinder against the number four. This is perhaps a good thing if you can duplicate it enough to trust it. The governor in the injection pump cannot cause this. If that first off capture is accurate. We may hopefully at last be getting somewhere. That makes sense. For cars with constantly rough idles I really think this system is excellent and easier to apply.

For those that perhaps are following this along. His posted first readings where. Front to back. 9.3mv 9.2mv 9.4mv 09.3. I correct this to that being his second reading. The first time the engine was at a differant temperature so in the 10.- mv range but still too close to call anything really wrong. The small swing between the number three and four cylinders did get my attention. It really was in a range that from experience the user would never know it. The threshold so far for a noticeable situation is a full half a milli volt off the common average or more. Yet if it was there. It could be a off reading glow plug a slight difference in injectors or the injection pump settings had aged a little. So you have to then verify the glow plug is not untypical as well as the injector by swapping them. Then if the results persist you know for certain where the problem is. You also have to do a compression check as a low cylider could be doing it. The important thing at that time is it was not going to enable an idle like he said he had. I wrongly assumed the readings where taken during the rough idle. It disturbed me so much it took me too much time to decide you could not have a rough idle or weak compression cylinders with that result. Nor be out of a power balance. It takes awhile to understand the milli volts never lie. Yet what I was seeing in concert with what the engine was doing. Lets say blew me away. After mentally considering this the only other thing that occurred to me is the primary timing might be way too far advanced. Making the engine idle run rough. That was totally eliminated as soon as I undertoof the idle was normal sometimes.

It is going to take a few at least milli volt tests to tie down what is going on when the engine is rough. Specifically what cylinder is being impacted for certain first. Catching it once is good but not enough to be certain. Something of an intermittent nature is going on here. If it pertains to this cylinder it may be hard to catch reliably. As it seems to be.

The last milli volt occasion was also a classic in another way. All his readings at one time where all over the place. Of course the engine was not running well. I wanted to see a compression check but from experience knew I could not get it. So I told him this just might be carbon buildup so drive the car and read the milli volts over some time. For some reason I was right as over time the numbers closed more all the time. They eventually stabilized yet even when they had they were not good enough. The engine was running better but still not that good in reality. So I mentioned there has to be a compression check. Before we go looking further. That was my last contact with him. We are not talking slight changes either. When I first looked at his posted numbers. My first thought was you could probably mix cement with that engine running.

I have to be fair though for a lot of people they have never done much work on cars prior to their problems. So I cannot be critical. For example the cost of a compression gauge may be financially straining in their situation. Many may not have the basic hand tools to work on cars either. Some members drive these cars out of financial necessity. I have no issue with people living within their means. Personally I think it is a good choice In general anyways.

Today was tough for me as along with a lot of other things. Yet another friend was admitted to hospital. They found far too many things wrong but will operate first thing tomorrow. Or that is the proposed plan late this afternoon. So he might have a chance as usually they do not operate when there is none at all. I have a feeling it is the end of the road for him unfortuantly. The first operation is to remove a portion of the obstructed bowl and leave him with a colostomy. Whatever is wrong is also in the liver and gallbladder and kidneys are poor. No mention of cancer yet but that is just a formality.

I am a huge believer of mercy killing being available on reasonable demand. It is not yet. Whatever life my friend has left I would not want myself.

Air entrained in diesel fuel can form vapor bubbles, especially at higher engine speeds (and if the fuel filters are dirty or partiallly clogged).
Air incursion (from cracks in fuel hose ends, loose fuel unions, etc.) is also more likely at higher engine speeds.

A small amount of air getting into the IP can cause a transient rough idle, until the air is eventually purged.
One would expect a greater likelihood of a rough idle after a hard run on a low tank.

Next time it does occur, check the clear hard lines for air bubbles by blipping the throttle to race the engine.
If the lines are brownish from fuel deposits, a flashlight beam directed at the hard lines can help to light up any air bubbles in the lines.

Hope your problem has a simple fix.

__________________
78 W116 300SD 'Desert Rose' new as of 01/26/2014
79 W116 300SD 'Stormcloud' RIP 04/11/2022

That it does change when it should not you already see. Your voltages where far closer to each other in the first test. i The thing is to catch it again at least one more time. When the idle is rough. Rather than describing it as jumping around. If this voltage only occurs or some similar difference from all the others. Only when the idle is rough. You know it has something to do with that cylinder or the system that supports it.


Conventional service methods would almost drive you over the edge trying to find this. As final proof if you need it. If you find it lower than the others. Let the rough engine run. As the engine is smoothing out the idle that voltage will be returning to what the others are. I have a very unusual test in mind once that injector it substituted with another. With the problem remaining there.

UPDATE:

I've finally sourced 4 new delivery valves (1 418 512 008) for a last crack effort at eliminating the shakes.
I installed one last night as a test on cylinder three. I did one only because I don't have fresh DV seals (1 410 105 020) and want to see if I develop a leak. I didn't lap it, just flipped it over and torqued to 50nm –previous torque was 45nm.

Here are photos of the new and the worn.



Initially, I was a little concerned they appeared so different despite being the same part number, though the main elements (the parts that count) calipered out the same. I did also read there were newer and older styles.

The old barrel/valve body (right) should be smooth on the outside. That rifling(?), I suppose came from years of spinning around in the pump, though who knows.



The plungers are interesting side by side. The old plunger (right) has a well worn ring around the bevelled edge which is supposed to form a tight seal with the bevelled edge of the barrel/valve body.

Due to the cosmetic differences (god I hope), it's difficult to pinpoint wear from design, but a few places on the business end of the plunger do appear quite eroded. Perhaps most markedly on the bottom fluting.

I'd like to drive around a bit more before installing the other valves to confirm I'm not leaking and trading one problem for another –so far so good however.

Stay tuned. This is getting comical.

__________________
1981 240D 4sp manual. Ivory White.

Anything is possible but a delivery valve should not be intermittent in operation. Worn ones can cause low power.

As a test see if your milli volts increased on that cylinder with the new delivery valve. In comparison to the others. That could indicate their general state.

I just finished a brake job on my beater this evening. Had real problems getting the pedal back. So I read up on the cars system. A lot of posts talking of real difficulties with this model. Almost a dealer service item. I just got lucky it was not the worse of them and I got it back. For a time it looked like I might have to use a dealer.

Makes you wonder and to add icing to the cake. The rear brakes are designed to wear out much faster than the front ones. There were also several suggestions not to use rebuilt back calipers.

So brand new calipers rotors and pads. Could set you back over two thousand at a dealer installed. At least it did not have the electric emergency brake where you have to put the computer into service mode to do the back brakes.

I have liked the car yet at the same time have to ask myself. What are some of these manufactures thinking? I also was really surprised at the amount of reports on the total random loss of the braking system. Starting when this model was still pretty new.

Older 2006 Jetta diesel still in really good overall condition. The prices I quote are Canadian. For example the rear calipers where 132.00 each for rebuilts. Rear rotors and pads 57.00. Front rebuilt calipers 100 each. Front rotors and pads 78 dollars. So 729.00 including tax for a pretty extensive do it yourself brake job.

If the last owner had changed the brake fluid more often I would not have had to do the calipers perhaps. Two where pretty draggy and the other two were not the greatest.

It is always cheaper to avoid issues while away and this car still gets around. Perhaps I should have kitted the front calipers myself other than I am too busy. At this time of the year.

From what I've gathered, the injection pump in general is a bit of a mystery to most people. I'll tell you what, if the DVs were simply a check valve, bosch could have saved themselves a lot of machining. They seem to hold and deliver a very precise amount of fuel. I imagine that if that fuel varies from cylinder to cylinder, over the course of a hard drive and less viscous diesel slipping past, I'm going to get all kinds of imbalance.

It's the only hypothesis I've found plausible -plenty in the archives, if anyone is interested. Meanwhile, at my level of marginal competence, I'm at the end of the DIY road if this ain't it.

RE: millivolts, they're all over the place, I'm not sure whether an increase or a decrease would be meaningful without a control value relative to the other cylinders. That particular cylinder has been +/-1.0mv habitually.

THAT SAID, I will certainly re-check readings after replacing the other three DVs and report back.

__________________
1981 240D 4sp manual. Ivory White.

The DV's are more than just a simple check valve. The funny shaped "hat" on top together with the non-fluted part of the plunger is designed to displace a certain amount of fluid standing in the hard line so that when the DV closes, it causes a sharp drop in pressure to guarantee a firm injection cutoff from the nozzle.

A good seal is essential, if the DV isn't sealing, fuel will leak back down into the pumping element when the plunger withdraws and cause a low pressure condition in the hard line. The result is less injection quantity than the better-sealing DVs. You see the results vary with operating temperature because the IP itself gets hot in use. Remember, there's a lot of friction inside it from parts moving around, and it's lubricated with engine oil. The fuel in the rack gets hot as well, hot oil thins, thin oil slips past poor sealing surfaces easier. That's one of the reasons why a DV "shake" is usually worst after a hard and fast highway run.

You've just discovered why I put zero stock in the whole mV test using the glow plugs. There's no control, and no reference value. The changes in the cylinders can happen quicker than you can test 4-6 glow plugs, so by the time you start at the front and work to the rear, the values can vary enough to be meaningless. Real thermocouples work against a calibrated impedance to induce a voltage. Your multimeter is typically in the megohm range and is not suitable as a calibrated impedance.

The only way the mV test is useful is to compare a before/after condition in a cylinder at exactly the same operating conditions. By that point you've already identified the issue and corrected it, typically noticed by means other than treating glow plugs as thermocouples.

__________________
Current stable:
1995 E320 149K (Nancy)
1983 500SL 120K (SLoL)

Black Sheep:
1985 524TD 167K (TotalDumpster™)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Just looking at the plunger's seat wear indicates it's toast and you'll likely get better running at the very least, I'm keen to see how it is after all are replaced .

__________________
-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

All four DVs are in place now. So far no leaks flipping and reusing the crush washers.

Before my report, something that concerns me is the seemingly arbitrary variety between pieces that all share the same part number. These are the new DVs:









And the old DVs:




Differences I've noticed. First and universal is the body of all the originals vs ringed body of the new. Relative to each valve:

Cylinder 1: Has an upside down "2" stamped on the body and shorter crown -the part that the spring sits on. (original has a 1, that is not upside down)
Cylinder 2: Has an upside down "1" stamped on the body and shorter crown (original has a 1, that is not upside down
Cylinder 3: Has an upside down "2", the shorter crown, a slightly different notch cut under the bevelled collar and right angles at the bottom of the fluting (original has a non-upside down 1 and diagonally cut fluting, and a notch like the originals). This is the only one that has the right angle in the fluting.
Cylinder 4: Has an upside down "1" (same notch as original, same fluting, same crown, but obviously different body).

Originals and new all have 112 008 printed on the top of the plunger (part number 1 418 112 008).

The plunger crowns, and body style seem less significant. The shape of the plunger fluting and the notch that I think allows drain back, seem more significant. Not sure how best to proceed.

After I installed them, I fired up the engine, and didn't see much improvement. A bit of intermittent nailing even. Drove around the block a few times, came home and tested millivolts for the hell of it. They were all over the place, most different by +/-1mv.

Drove around a bit more that night but this time on the highway and checked millivolts again. Less variation this time. Today, after a highway run and some local driving the nailing seems to have disappeared and although I can still feel a very subtle sway in the cabin, at this point I'm not sure that isn't normal. For reference, it actually is a little smoother sitting in my car than my buddies Tacoma. I also checked Millivolts again, and this time the difference was only +/-0.2mv which appears to be almost balanced. I also feel less vibration in the seat rest although that's difficult to quantify.

I have read a few instances (I think from you Diseasel300) that sometimes doing stuff in the pump takes a certain number of miles to "settle in"? I don't understand what that process would entail but there appears to be some validity to it.

__________________
1981 240D 4sp manual. Ivory White.

Where I am interested if the milli volts are still not constant on that cylinder. In relationship to the others. If the voltage now remains constant or the intermittent rough idle is gone. It was the delivery valve.

That the voltage was not remaining constant all the time in relationship to the others. Meaning there was something going on there of an intermittent nature. Intermitent conditions are much harder to find usually.

The I milli volt swings are a pretty massive swing. Easily creating a rough idle.
The intermittent problem is still unknown. Yet you do have the cylinder identified. I assume without verifying that is the cylinder you installed the new delivery valve on.

I was wondering if an intermittent delivery valve was even possible. If there is enough wear on the guidance shaft. It could hang up on the wear ridge sometimes I suppose.

The problem I had with that is on the next injection stroke for that cylinder it is pushed open again. Unless it remains just hung up on the ridge if there is enough room open for the fuel to get by. So it then is not moved.

You can change all the other delivery valves but that will have no impact on the number three cylinder issue. It will still be there with the new delivery valve installed. If it is remaining since you changed the valve.

I have been working through a test sequence possibliity in my mind. For delivery valves in place on the engine. I have to refine it some yet. Anyways it goes like this. You remove the feed line from the injection pump to the injector. You take a dedicated line configured to your needs. Attach the new line from the injection pump to a spare injector. It does not matter Just about any injector from a junk engine should be fine. Probably pulling the glow plugs out to decrease turning resistance.


Turn the engine over until that injector sprays. Stop. Mark the harmonic balancer with a marker at the pointer. Then rotate the engine 360 degees until that mark is back at the pointer again. This guarantees the input port to the pump element is open. As the crank in the injection pump has moved 180 degrees.


Remove your test injector. Attach your pop tester to the line. Pump it up to say two thousand pounds pressure. Watch just how well it holds it.

Any pressure escaping past the valve will exit through the element fill port and then through the relief valve safely. You may want to loosen your fuel cap but we are talking small volumes here. A marginal or really poor relief valve is still not going to want to even pump up to high pressure. You couple up and start to pump up. You gain some pressure indication and watch that it is holding. Then take it up if it is. To 2000 pounds.

Through experience we would find out just how much leakage past the delivery valve if any is allowable. My guess is we would aquire a lot of information along the road. A low volume metal to metal check valve should really have a very, very small amount of seat leakage if any. For those that own a pop tester already they could consider it.

The question in my mind is the test worth the time and effort? At the same time as these cars age. Those valves like all check valves will wear.

You could aquire all the components to do this test probably cheaper than a set of new relief valves. Then you have to pop tester to do your own injectors. The test could indicate that 3 of the 5 you test are in great shape for example. The two you found that have enough leakage to get your attention. Remove and try to resurface the check valve. Then test it again to see if you solved the issue.

Or you could pull and try to resurface all five. Or buy five new ones. Not having any solid indication they were the issue to start with.

Buying a new set of delivery valves or dealing with them some other way. When you really have no ideal of their condition to start with. Is not really the way I like to do things. Typically a lot of posts go. I changed a whole list of things but still have the problem. That is usually because tests to isolate it where not engaged.

Finally I believe miili volts have established what cylinder is causing the intermittent rough idle. If that one cylinders milli volts drops off by one volt only when the rough idle is there. In comparison to all the others.

Without milli volts I have no ideal of just how you could narrow it down to this. The cylinder is not going totally dead or the milli volts would have dropped more. Unfortunatly it is also an intermittent condition.

Other than an intermittent delivery valve. I do not think it is the injection pump and I hope he has swapped injectors. With that cylinder . Watching for the voltage drop to occur on the other cylinder instead. With that intermittent cylinders injector in it. When the engine is rough.

Milli volts value is to get you into the right area a lot faster on many types of faults. You just cannot use shortcuts when applying this tool. Most of the time it can just reduce the search effort for where the problem is. Sometimes it can lead you directly to the component. It to me is nothing special really. I see it as just another tool. No tool can do it all.

Thanks Barry, these are all great thoughts. I should add however, that the more I tested the more I learned cylinder three was an anomaly. In other words, it was never consistently an issue. Sometimes cylinder one would be up, or two, or one and four etc. so while the seemingly odd delivery valve is placed on cylinder three, my latest testing did not show any issues there. I believe my values were 9.6, 9.4, 9.6, 9.5 or there abouts. I didn’t record them, only the relative difference which was +/-0.2

__________________
1981 240D 4sp manual. Ivory White.

Great write-up,Good thoughts,Yes a good test tool.
I would use if having problems.
Just to share a tip,jumping pump can quickly be determined:push down on throttle
stop note if engine smoothes out as rpm slows,if so pump is oscillating.
A injection pump not coming to full idle stop can cause jump also,pop off linkage.
A partially clogged pre chamber might cause problems also.
Just sharing possible ideas to speed things along.

I posted my prior post before reading the posters last one. Actually two back.

Well if your voltages are already only around .2mv different across the board pretty much constantly now. It sounds like there is hopefully no more really rough idle occurring.

If this hopefully continues it almost had to be that one delivery valve was intermittently hanging up somehow. A visual inspection of it might show something. Do not throw the old ones out. Grease them and stuff them in a ziplock bag. Just be sure to put the suspect one in a separate bag if you can.

Your intermittent problem was frequent enough that as soon as you are positive it is gone post it please. Plus you have added to the store of knowledge. That is the most important component of this. Besides getting your car running better.

I was totally unsure about the context of milli volts and delivery valves before personally. It looks like you might have gotten away with just the number three delivery valve. With some indication the number four might have had a lesser issue. I would have to look back to be sure the correction may have been only nominal.

I have a strange relationship with milli volts. They do not lie and at times will take you to places you do not want to go. There is always the nagging problem that they will force you to look at a problem at the same time.

Hindsight is a wonderful thing. If this repair exercise had been started with an accurate compression test and milli volts. It could have been run down faster. His first posted milli volts where telling me the first compression check was wrong to start with. Off site and was mentioned there was no sense going on until it was redone by me.

Sorry about the tortuous frustrating route you have been over with this problem. I hate to quote this. Milli volts are somewhat like a religion. You either believe in them or not. Once you can see them as a useful tool it is hard to ignore them.

Every single case so far on what to expect with certain readings. In your case if the problem stays away. It is pretty well proof that an intermittent delivery valve can be a reality. I thought before this that was a pretty remote possibility.

Not a total one but close enough to it. That to me is well worth knowing. I do not see your early issues with this problem as wasted time and effort. You did a pretty comprehensive maintenance run on an old fuel system. This seriously adds to overall reliability.

Plus I am getting pretty old and hopefully younger people like you will keep the concept of milli volts alive. It is just too useful a tool to be forgotten with time.

If other people I have respect for can wait until the exercise is over before being critical of the system. I will participate as much as possible assisting members with some of their issues. If the use of this system is indicated.

There have to have been at least fifty or more posters it would have helped that I could not respond to. Since the initial batch on and off site.

In the vast majority of those cases they could not even establish where their problem was. Instead there usually was a long extensive list of parts replaced. With no indication at all they were bad. I am of the older school as well.

I initially went off site with this system. Then thought lets give it a chance again and came back on site. It is where this system belongs. If it gets people into the area where the problem is faster. Or indicates what it is not.

This poster already suspected the presence of a delivery valve issue. After a lot of preliminary work. All milli volts really did was clear a lot of other possibilities. Plus indicated it was directly related to the third cylinder. Clearing other possibilities is probably the strong point of milli volts.

I do not think I will ever forget the video of his idle he posted. We had a poster once where his wife or girlfriend complained of her boobs shaking uncontrollably in his car.

I was going to post a survey. If we should try to help him fix the issue or not. Although I already knew what results the survey would produce. This posters idle in his video was in a similar category.

Incidentally if it had not occurred to the poster.. The erratic milli volt readings after the delivery valve changes. Where probably just a result of entrained air in the injector lines slowly clearing out. I am seldom certain of many things but this is my best guess. From his last description I suspect he thinks the primary problem is gone at last.

I went back and read your last post. It indicates you may see better fuel millage as well hopefully. Delivery valves that are not sealing well in effect retard the basic engine timing. Your tests are also showing that old delivery valves may not just have a fixed leakage rate. This is not the best news for others. I will have to think about this for awhile.

You again have been the fastest so far to pick up on using milli volts. It is a pure comparative system. Sometimes people just do not get that. So the differences in comparisons are the primary thing to understand. Plus the effect of shortcuts in collecting them can create.

A good solid properly power balanced engine will not show individual values changing in relation to others. We saw many examples where a 5.9 5.9 5.9 5.9 was read for example. After correction. When the voltage numbers changed they all changed in lockstep. There is no place for a fixed reference in the use of them. Or any use in having it. Your refferance remains floating. Sometimes when investigating things I found it useful to do a variety of things. Each case always offered something to learn about.

I started totally cold and for sometime it was hard to even get some things to work well. What your case has impressed on me is erratic individual voltages. In comparison to each other is something not seen or reported before. It may have been missed by others but I doubt this.

Yet this is to be expected with intermittent problems. Yours was the first one. I am probably a slow thinker. Yet in future tests if erratic comparison voltages are found. Serious attention might be warranted in looking at the delivery valves. Or if it just is not there then they may be considered fine. Now if the erratic swings where only around .1 to .2 mv I would think it allowable. At .5mv they would become operationally noticeable is a yardstick of dubious worth. I have used without a much higher sampling. Your number three for example was way past acceptable limits. when it was erratic. I should have picked up your number one you reported as well. There just was no history with milli volts and delivery valves. Plus at the time the erratic varience was only.4mv I thought. Plus I was not totally familiar with the probable cause instead fixated on your number three that had a major issue.

So there may be a very simple way to check. What general condition the delivery valves are in. We already know how to deal with element issues in injection pumps. The problem with mili volts is the more you learn the more there is to learn. On a preliminary first reading it indicates more and more after every case is finished to me. Now I add erratic readings to the mix. It may be time to start writing up what initial readings in comparison really generally indicate.

Long long posts in an attempt to get well past this does not work concept. It is all we really have had in many cases even so far. In far too many cases otherwise the injection pumps would have to have in gone for a rebuild. Or a good used pump sourced. You can do comparative element restoration if the need is indicated. You have a refferance to where you start and where you are going to compensate for some aging issues. You can always go back to where you started. With milli volts.

The human ear is both crude and generally useless as you would not even know where the problem is without milli volts. Or even what you are trying to correct. So far it has been limited to doing only one element. On an injection pump. Plus there are quite a few things to do before you start.

It should not be done unless a fixed approach that eliminates any other possibility is used. For those that followed the program it worked. There was one guy in Europe that did his whole pump. Only mentioning it to me after. I would have discouraged him had he let me know what he was going to do.

Initially my thought was that if we did not do it. The pump was going to a shop or being replaced. If it did not work then it was still going to a shop. What surprised me is that it worked every time of all the cases I was involved in. Nothing has changed. Unless you do all the proceedures that are required to prove it is the injection pump. You should not do it. Although you have risked nothing. There are still things to be learned in this area I think.

I had this morning at the cottage to really consider just how important this poster has been. It is almost a slam dunk that if you are not processing air and your milli volts are erratic. Delivery valves may be suspect.

I may change my mind after some time. Yet for the time being his persistence in using milli volts has made it a possible test for poor delivery valves. This is a quantum leap if it proves out. It very well may as many other things have also proved out over time using milli volts. I also think it is time to clarify what using milli volts is. Essentually it compares the temperature of any cylinder with any other in a dynamic fashion. I originally set out to do the timing on injection pumps by this method. This was a failure but led to using it for the basic engine.

It is a pure comparative system. Or floating value system. The only important thing is making sure the glow plugs are not old as they then produce differences from each other under the same conditions. We may have got a break with a delivery valve check test.

Using old existing glow plugs. You unplug the glow plug harness. You read and log all the voltages. Repeating this to see if they are all staying the same relative to each other. For example you might get 5.8 6.6 4.7 and 6.1. With old glow plugs.

Were with new ones from the same batch might produce 6.1 6.0 5.9 6.0. With your old plugs you want to let the engine run and record the numbers say every 10 minutes apart. After the engine has warmed up. What you would be looking for is a change in a recorded Milli volt value that is not reflected in the others. For example if a voltage value drops or increases more than .5 milli volt while the others did not. If you are pretty sure you are getting no air in your fuel system. You can never be certain. We may have a simple test for the general condition of the delivery valves.

It is so simple to read the milli volts and no special preparations are required for this test. So far with all the other tests besides this posters. The numbers have always remained almost rock solid in comparison to each other. In a way constantly logging the fault if any.

My thinking this morning was what else but air or those delivery valves could cause erratic readings. All we need is a batch of members to try the test. You will not hurt anything. Bad delivery valves can hurt power and otherwise present no real attention getting symptoms. Yet they should present as erratic milli volts on at least one of the readings. The discovery the poster made that was of great signifigance. Delivery valves can be intermittent in function. This still kind of suprises me but it seems to be true. Milli volts can easily pick them off I think.

If some members try this. Remember that the milli volt numbers you get are not to be trusted with old glow plugs. It does not mater what they are. We are looking for changes in comparison to what you have that are unusual over perhaps a half hour series of readings after the engine has warmed up. Or the engines idle sound has changed.

I am moving faster on this as there has been so much posted on delivery valves reciently. New ones cost money and why speculate on their need if a simple test can inform you of the probability existing. That one or more needs dealt with.

For every other test existing so far you need usually a new set or very recent set of glow plugs from the same production batch. Even then on rare instances they have to be swapped around to verify they produce the same milli volts under the same conditions in another comparison test.

Last but not least post any information if you do try it. The numbers you post with an older set or mismatched glow plugs are in themselves meaningless. Any changes at the same time in relationship to each other can be of a lot of interest. Something of an intermittent nature is going on even if you cannot hear of feel it. You will know the cylinder and it may be the delivery valve. Remember all milli volt testing is dynamic in nature.

That is why it is so good at finding out the condition of a fuel injector. You just buy some new crush washers and run each injector on the same cylinder at idle and at elevated rpms. If your voltages remain similar from injector to injector. Using the reading from another to verify the test standard. Your set is still fine.

Or marginal injectors can show up in just the normal power balance readings. Where you swap it with the neighboring injector to verify it is bad or clear it. No more guessing.

Why is this so important? Delivery valves are a wear item. I believe you can find out if yours are still good or not pretty easily. Unless some new information comes forward it almost appears the poster had two delivery valves that where intermittent performers.

Odd behavior from a check valve. One that is constantly bad will show up as a constant low cylinder voltage reading. Being just one of many possibilities for it. For that test you do have to have a good set of glow plugs.

I may as well keep going with some input semi stealing the thread even more. Just in case anyone is interested.

We need users information to increase the current abilities of using this system. I have unfounded suspicions. That my approach is only touching the surface of using milli volts.

.I have observed something that may or may not be true. I can only suspect it as other than this gentleman in all the previous cases no compression checks were done.

There is a possibility we may have doctored some injection pump elements to apply more fuel to cylinders with weaker compression. Increasing their power levels to match the rest.

This is based on we had just too much success primarily at the start. All odds where this should not have happened. Plus the European gentleman took a freshly rebuilt pump and installed it on his engine. Then recalibrated it to match his engines condition. He seemed to be happy with the results and I may have been wrong in hindsight in being so critical of what he did.

There were too possibilities to me. The calibration of a rebuilt injector pump is intended for a mechanically perfect engine and injectors. His engine may have had some issues the readjustment masked. Or milli volts are more accurate on setting up a pump than the mechanical method. This is a very weak thought. What sticks though is with posted compression checks and numbers we may be able to adjust for some compression losses. The adjusted cylinders where required will only be running at the same temperature as the others after correction. So we are not overheating that cylinder. We are just increasing the power.

For example the critic of the system or another poster reciently posted. He was not really happy with his idle and wrote it off to one cylinder having 30 pounds less compression. At one time.

Without using milli volts you cannot really determine what the cause really might be. If it turns out it is that lower compression cylinder. It may not be and the milli volts would indicate that. Yet if it is and a few things are eliminated. Some fuel increase might bring it back on line with the other cylinders. I am really interested in what is really possible in this particular area.

For those that have these cars and lets say simply because they like them. At todays costs it would be a nominal cost to buy the number of cheap digital voltmeters you have cylinders. At five dollars apiece or less. Figure out a way to configure a plug into the glow plug harness and attach a cable long enough to get back inside the cab. You could read all cylinders milli volt outputs at a glance.

As for the poster of this thread. His compression is not typical of a really excessively high milage engine. I do not know why his delivery valves where so worn. His primary issue may be gone. Another look at those numbers could indicate there is room to further improve the idle. Or if he is satisfied with things as they are is also fine.

With delivery valves so worn there is a possibility wear also occurred. In other components close to it. To go further though involves some work in verifying all his glow plugs generate identical voltage under identical conditions. The .2 mv swings currently may or may not be true in reality. Swapping glow plugs to verify them is somewhat tedious. So the effort depends on the individuals desire. All that is certain so far is it looks to him like he has .2 volt differentials.

That may be perfectly true but just not verified. The important thing is if he is now satisfied that is the only thing that really matters. Good enough is a quite reasonable situation to me. I guess I would quantify it as a coarse milli volt check with decent glow plugs over a very critical check that involves more time. I read what he had done originally and his glow plugs where only a year old. The problem was so bad I felt it was pretty safe to use his glow plugs without verification they were well matched.

If this system does not work I have wasted a lot of time. If we can go more mainstream with it. Since with every case something has been learned. We jointly can develop it further.

We are probably going to gather some really useful understandings as well. . I already have a lot of questions with no answers. It takes the participation of many to get those answers.

Diesel powered cars are going to rapidly fade into history I suspect. For those that persist in wanting to keep them long into the future. You may need to increase the knowledge base of how to do this. Garages may turn them away at some point.